Sinemet-ferrous sulphate interaction in patients with Parkinson's disease.
1. This study examined the effects of administering ferrous sulphate 325 mg with Sinemet (100/25 tablet) on levodopa and carbidopa bioavailability and on signs of Parkinson's disease in nine patients. 2. Ferrous sulphate ingestion with Sinemet resulted in a decrease in levodopa area under the curve (AUC) of 30% (P less than 0.01) and a greater than 75% decrease in carbidopa AUC. Despite a strong relationship between reductions in levodopa AUC and reductions in Sinemet efficacy (r = 0.83, P less than 0.01), the average reduction in Sinemet's efficacy associated with ferrous sulphate did not achieve statistical significance (P = 0.055). 3. Chemical studies indicate that iron forms chemical complexes with carbidopa in a similar manner to levodopa and is a likely mechanism for the drug interactions. 4. AUC when a Sinemet tablet is taken concurrently with a ferrous sulphate tablet appears to be clinically significant in some but not all patients. The clinical significance of repeated ingestion of ferrous sulphate with Sinemet requires further studies.
Campbell
N R
NR
Discipline of Medicine, Faculty of Medicine, Memorial University of Newfoundland, St John's, Canada.
Rankine
D
D
Goodridge
A E
AE
Hasinoff
B B
BB
Kara
M
M
D000328:Adult; D000368:Aged; D000978:Antiparkinson Agents / Q000493:pharmacokinetics / Q000494:pharmacology*; D001682:Biological Availability; D002230:Carbidopa / Q000493:pharmacokinetics / Q000494:pharmacology*; D004338:Drug Combinations; D004347:Drug Interactions; D005260:Female; D005296:Ferrous Compounds / Q000494:pharmacology*; D006801:Humans; D007980:Levodopa / Q000493:pharmacokinetics / Q000494:pharmacology*; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000378:metabolism; D010300:Parkinson Disease / Q000188:drug therapy / Q000378:metabolism*
D000978:Antiparkinson Agents; D004338:Drug Combinations; D005296:Ferrous Compounds; C009265:carbidopa, levodopa drug combination; C020748:ferrous sulfate; D007980:Levodopa; D002230:Carbidopa; D010100:Oxygen